\usetikzlibrary{positioning}

\begin{tikzpicture}
  \node[] (n1) at (0,0) {(1) \enspace$x=1$};
  \node[below=1.2em of n1.west,anchor=west] (n2) {(2) \enspace lb $a$};
  \node[right=7em of n2.north,anchor=north] (n3) {(3) \enspace $t_{1}=x*5$};
  \node[below=1.2em of n2.west,anchor=west] (n4) {(4) \enspace $r=t_{1}$};
  \node[below=1.2em of n3.west,anchor=west] (n5) {(5) \enspace $t_{2}=x<10$};
  \node[below=1.2em of n4.west,anchor=west] (n6) {(6) \enspace if ($t_{2}$)\_};
  \node[below=1.2em of n6.west,anchor=west] (n7) {(7) \enspace $t_{3}=x+1$};
  \node[below=1.2em of n7.west,anchor=west] (n8) {(8) \enspace $x=t_{3}$};
  \node[below=1.2em of n8.west,anchor=west] (n9) {(9) \enspace gt $a$};
  \node[below=1.2em of n9.west,anchor=west] (n10) {(10) ie \_};
  \node[below=1.2em of n10.west,anchor=west] (n11) {(11) $r=0$};

  \draw[->] (n9.west) -- ([xshift=-1.5em]n9.west) -- ([xshift=-1.5em]n2.west) -- (n2.west);
  \draw[->] (n6.east) -- ([xshift=1.5em]n6.east) -- ([xshift=1.5em,yshift=-4.8em]n6.east) -- (n10.east);
\end{tikzpicture}